LEMS Case Review

David Gerber, MD: That’s a great overview of the condition. We have several cases to discuss. The first one is of a 64-year-old man who’s admitted to the hospital with a 3-month history of shortness of breath, fatigue, and difficulty standing up from a chair. He said his legs felt weak, and he’d been having trouble climbing the stairs in his house for the past month, especially in the evening. His medical history is significant for about 40 pack-years of smoking since the age of 25, chest imaging is performed and the CT scan shows a subcarinal mass. A bronchoscopic biopsy is performed and demonstrates small cell carcinoma. He’s referred to medical oncology and neurology, and the neurologist orders the antibody study, the voltage-gated calcium channel, which is positive, suggesting Lambert-Eaton myasthenic syndrome, or LEMS.

Let me start by thinking about this as a small cell lung cancer case, which is a minority of lung cancer cases. It’s about 15% of lung cancer cases; 40 years ago it was 30% of cases. Why is the incidence falling? It’s the type most closely linked to heavy tobacco use, especially unfiltered cigarettes. We learn in medical school that small cell lung cancer is the most aggressive type of lung cancer, but it is also the most responsive to chemotherapy and radiation. When someone’s in the ICU [intensive care unit] with small cell lung cancer, on a ventilator, the answer is never hospice. We will give that patient chemotherapy, and it’s likely that they could come off the ventilator within 48 hours. The issue is that, almost universally, it will recur in the future. At that point, it’s extremely difficult to treat.

Considering this case, so far there’s a mass in the chest that’s small cell lung cancer. I’ll want to do a brain MRI [magnetic response imaging] and a PET [positron emission tomography]/CT scan. If this is limited to the chest, what we call localized disease or limited-stage small cell lung cancer, we will treat it with concurrent chest radiation, thoracic radiation, for about 6 weeks, and 4 cycles of platinum-based chemotherapy, typically cisplatin and etoposide. If you think people are doing well, following the completion of that treatment, we may offer them prophylactic cranial irradiation, that’s whole-brain radiation, after the chemotherapy is done, to decrease the likelihood of future brain metastases. Doing that is also associated with improved overall survival.

What if it’s not limited stage? What if when we do additional staging, we see cancer outside of the chest area, like two-thirds of the extensive-stage cases that are diagnosed in small cell lung cancer? We will leave out the chest radiation, and we’ll give a platinum and etoposide chemotherapy. But today if the patient is considered eligible, we would also add an immune checkpoint inhibitor, immunotherapy, which is given at the same schedule every 3 weeks as the chemotherapy, but is continued as maintenance therapy after the chemotherapy is finished. How would I factor in the different options for patients who might have a paraneoplastic neurologic syndrome? With Lambert-Eaton myasthenic syndrome, I have to ask myself, would cisplatin possibly make it worse, and would giving whole-brain radiation possibly make it worse?

Transcript edited for clarity.